get the memorycache factory from OCP\Server instead of a cache instance

this allows apps to specify a prefix to use

lib/private/server.php

@@ -136,10 +136,9 @@ class Server extends SimpleContainer implements IServerContainer {
 		$this->registerService('UserCache', function($c) {
 			return new UserCache();
 		});
-		$this->registerService('MemCache', function ($c) {
+		$this->registerService('MemCacheFactory', function ($c) {
 			$instanceId = \OC_Util::getInstanceId();
-			$factory = new \OC\Memcache\Factory($instanceId);
-			return $factory->create();
+			return new \OC\Memcache\Factory($instanceId);
 		});
 		$this->registerService('ActivityManager', function($c) {
 			return new ActivityManager();
@@ -303,10 +302,10 @@ class Server extends SimpleContainer implements IServerContainer {
 	/**
 	 * Returns an ICache instance
 	 *
-	 * @return \OCP\ICache
+	 * @return \OCP\CacheFactory
 	 */
-	function getMemCache() {
-		return $this->query('MemCache');
+	function getMemCacheFactory() {
+		return $this->query('MemCacheFactory');
 	}
 
 	/**

lib/public/cachefactory.php

@@ -0,0 +1,17 @@
+<?php
+/**
+ * Copyright (c) 2014 Robin Appelman <icewind@owncloud.com>
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ * See the COPYING-README file.
+ */
+
+namespace OCP;
+
+interface CacheFactory{
+	/**
+	 * @param string $prefix
+	 * @return $return \OCP\ICache
+	 */
+	public function create($prefix = '');
+}